<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .row {
      height: 70px;
      box-sizing: border-box;
      padding-top: 40px;
      border-bottom: 1px solid #888;
      margin-left: 32px;
      margin-right: 32px;
    }

    .input {
      width: 100%;
      height: 20px;
      border: none;
      line-height: 20px;
      font-size: 16px;
    }

    .btn {
      height: 50px;
      margin-left: 32px;
      margin-right: 32px;
      margin-top: 32px;
      background-color: green;
      color: white;
      line-height: 50px;
      text-align: center;
      font-size: 24px;
      border-radius: 8px;
    }
  </style>
</head>

<body>
  <div class="row">
    <input id="username" class="input" type="text" placeholder="用户名">

  </div>
  <div class="row">
    <input id="password" class="input" type="password" placeholder="密码">

  </div>
  <div class="btn">
    登录
  </div>
</body>

</html>